On 15/09/2009, Uwe Ligges <lig...@statistik.tu-dortmund.de> wrote: > > > e-letter wrote: >> On 14/09/2009, Steve Lianoglou <mailinglist.honey...@gmail.com> wrote: >>> Hi, >>> >>> On Sep 14, 2009, at 9:47 AM, e-letter wrote: >>> >>>> Readers, >>>> >>>> I have been reading the r book (Crawley) and tried to use the >>>> influence measures function for linear regression, as described. I >>>> have one datum that I wish to show in the graph but exclude from the >>>> regression and ab line. >>>> >>>> x y >>>> 0 5 >>>> 10 9 >>>> 20 10 >>>> 30 19 >>>> 40 4 >>>> >>>> With the influence measures function I plot the graph but linear >>>> regression includes the datum (40,4), which I want to show on the >>>> graph but exclude from the linear regression ab line. >>>> >>>> Is there an alternative package to perform this task please? >>> Please post the code you're using to try and do the regression. >>> >>> I think you simply want to remove the data point when you build the >>> regression model, then plot it later after you plot the regression. >>> >> Correct; below are my commands: >> >> x<-c(0,10,20,30) >> y<-c(5,9,12,19) >> fit<-lm(y~x) >> plot(y~x) >> abline(fit) >> >> I try these commands as explained in section 12 (graphics) of the >> introduction manual: > > > > Hope this example is not in Crawley's book as you cite it, because you > need to make the plot large enough to include the value (40,4) already > when you create the plot, e.g., by specifying xlim and ylim. > No, it is an example I made quickly to post to the mailing list. Which section of the manual explains xlim please?
> Anyway, I'd rather explude the value from a data.frame as fol#ows: > > # whole data: > dat <- data.frame(x = c(0,10,20,30,40), y = c(5,9,12,19,4)) > dat > plot(y~x, data=dat) > # fit the regression without the 5th observation: > fit <- lm(y ~ x, data=dat[-5,]) > abline(fit) > Thank you. Please advise which section of the introduction manual explains how to exclude a datum (the instruction '...dat[-5,]'. One of my biggest difficulties is finding the relevant section of the manual(s). ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.